Travelling bridge type clarifiers or settling tanks have heretofore required heavy, expensive, and bulky installations with transverse bridges moving the full lengths of the settling basin or pond. Sludge removal devices were suspended from these bridges requiring an unimpeded travel path through the length of the pond or basin. These devices took the form of scrapers pushing sludge settled to the bottom of the pond or basin into sumps or mechanisms operating with pumps, air lift or siphon devices. These scrapers or other removal mechanisms in serving the full length of the basin or pond required longer time intervals between periods of sludge removal at the inlet thus permitting relatively deep accumulations of heavy sludge that could not be efficiently removed. The movement of scrapers or the other removal devices through this heavy accumulation stirred up the sludge to decrease the settling efficiency.